[boringssl]: Merge latest chromium-stable branch from Google.

diff --git a/external/boringssl b/external/boringssl
index 2bc26c2772ad0a5d6b0ad4ba2ec77c8183d8932d..9ad688f0ae679b32e9c0a9b21bb63a4488c28b6b 160000 (submodule)
--- a/external/boringssl
+++ b/external/boringssl
@@ -1 +1 @@
-Subproject commit 2bc26c2772ad0a5d6b0ad4ba2ec77c8183d8932d
+Subproject commit 9ad688f0ae679b32e9c0a9b21bb63a4488c28b6b